Nope. That's just an auxiliary bin for smaller things! The other side contains your 12V accessory battery. In addition, you can store your tonneau (roller) cover under the floor if you need to carry something large in the boot with the rear seats folded. That notch you see in the small box (top of the picture), that's where one side of the bar goes.
I would post a comment as to what to put in there, but, I want to stay an active member.............LoL
Had my car 3 years and did not know that. That roller cover comes in handy sometimes and other times is just plain in the way. I have plenty of room to store it that way!
My PiP has the compressor and tire sealant in there. They are still in their original sealed plastic bags, thankfully. I have tire plug tools and a Slime compressor down in the luggage cover hole. iPad ?